Police are continuing their investigations into the death of 16-year-old Jodie Muir after initial reports suggested she had taken an ecstasy-type tablet at a gathering on Friday night.
The teenager's mother, Laura McArthur, has now claimed her daughter was drug-free but suffering from a heart condition.
Ms McArthur took to social media in an attempt to explain what had happened to her daughter after others posted unpleasant comments about the teenager.
She said Jodie, understood to have lived in Glasgow's east end, had a rare condition called Long QT syndrome, which can cause abnormally rapid heart rhythms, sometimes resulting in death.
Posting on Police Scotland's Facebook page, Ms McArthur wrote: "I am (her) mother and my daughter's post mortem has concluded and Jodie died of heart failure due to Long QT syndrome."
She criticised those writing "vile words and heartless comments" and said: "Try finding out facts and not open your mouth and write stuff you know nothing about."
She added: "Jodie never took any drugs. Jodie had a heart condition called Long QT syndrome and had been unwell and her heart failed just the same as my nephew 13 years ago so please let us as a family grieve and try and understand why we will never see our beautiful baby again."
Jodie's aunt, Linda McArthur Congalton, also asked other Facebook users to be careful about what they were saying.
She wrote: "I'm her aunt and she passed away. Nothing has been proven yet. We have a heart condition in the family so if you can't send your condolences then keep your comments to yourself."
Police initially put out an alert warning about the danger of drugs in the wake of Jodie's death in Rutherglen. The original statement, said it had been suggested Jodie may have taken an ecstasy-type tablet.
Last night, Chief Superintendent Ciorstan Shearer, of Police Scotland, said inquiries were continuing, to establish whether the teenager died as a result of taking drugs or from natural causes. She said: "I know that this is a very painful and upsetting time for the girl's family and friends and Police Scotland will do all we can to support her family at this difficult time.
"I do not yet know whether drugs have played a part in this tragic death and it is therefore important to trace other party-goers to establish that they are safe and well."
Around 40 to 50 teenagers are believed to have attended the party. Ms Shearer added officers have managed to speak to a "significant number" of them, but called for others to get in touch.
NHS Greater Glasgow and Clyde Consultant in Public Health Medicine, Dr Anne Scoular, said: "Many drugs are unregulated and no one knows what they contain or the effects they may have. I would urge anyone who has taken drugs and experiences symptoms such as a high temperature, aggression and muscle pains or begins to feel unwell or feels a more intense high to seek immediate medical help."
Jodie's family told of their heartbreak over her death.
Mrs McArthur Congalton posted messages on her own Facebook page saying the family was "in a state of shock". She added: "It's with a heavy heart I write this post. RIP my gorg niece Jodie, will love and miss you. Forever in our hearts."
Friends also posted on Jodie's own Facebook page offering messages of condolence.
Samantha McHardy wrote: "Rest in peace beautiful, still don't believe it, you were such an amazing girl with your whole life ahead of you. Breaks my wee heart that I'll never see your wee face, or hear some silly story that you've got to say. Sleep tight princess xx."
Caragh Scott also posted: "Miss you forever. I'll never forget your beautiful face. Sleep tight angel."